Microorganisms such as bacteria are capable of growing by combining on the surface of inorganic substrates, forming a biofilm. This mode of growth is directly involved in a large number of bacterial infections, which may arise, for example, in the food industry sector, via pipework, or in the medical sector, during the insertion of prostheses or implants.
To prevent the formation of biofilms, it is known practice to modify the surface of inorganic substrates by grafting molecules with antimicrobial properties, or molecules that release groups with antimicrobial properties. Organosilicon coupling agents have been used to this effect for many years.
However, organosilicon agents cannot be used for all types of substrates. For example, they are unsuitable for substrates of phosphate or calcium carbonate type. In addition, the process for forming such coatings is complicated due to the fact that these organosilicon agents are moisture-sensitive. Furthermore, the coatings obtained with these coupling agents are moisture-sensitive, in particular in basic medium.
To overcome these drawbacks, the inventors have found that it is possible to use organophosphorus coupling agents to bind to various substrates groups with antimicrobial properties or capable of releasing a component that has antimicrobial properties.
This solution has many advantages over the prior-art techniques.
Firstly, it is possible to treat with the same coupling agents a very wide variety of substrates (metals and metal alloys, metal oxides, metal hydroxides, and metal carbonates and phosphates). This makes it possible especially to satisfy the needs in the medical sector, in which no satisfactory general solution had hitherto been found for reducing the risks of infection following the insertion of prostheses or implants, in particular on account of the very wide diversity of materials used. In addition, it is thus possible to treat a complex object constituted by different materials, or to treat objects of the same family each constituted by a single material which may vary from one object to another.
Moreover, the grafting process may be performed under easier conditions than those of the prior art, for example in ambient air, under non-anhydrous conditions, or even in water, which makes it possible to avoid the use of organic solvents.
It is also possible to prepare surface coatings that are very stable in the presence of water, and even at basic pH, allowing sterilization by wet autoclaving or washing with a basic disinfectant such as bleach.
The search for and development of a solution for the production of coatings for objects intended to be used in the medical sector may be transposed to the production of industrial objects, such as taps or valves constituted of several materials, or of objects constituted of materials that may vary, such as steel, zinc steel or copper pipes, these objects being intended, for example, to be used in cooling towers or hot water distribution circuits. The possibility of working in water makes it possible to envision a treatment by simple circulation, in an existing installation, of a dilute solution of the coupling agent in water.